1. Field of the Invention
This invention relates in general to bicycle speedometer tire drive gear adaptor assemblies and more particularly to an improved and economical bicycle speedometer tire drive gear adaptor assembly.
2. Brief Summary of the Prior Art
Bicycle speedometer drive assemblies are usually mounted on one of the bicycle wheel axles to transmit movement of the wheel adjacent the axle to the speedometer. This arrangement, however, does not provide accurate speed indications since actual bicycle speed depends on the wheel diameter.
Providing an axle mounted speedometer drive for accurately indicating bicycle speed requires a gear adaptor assembly individual to respective wheel diameters, and this is expensive. Employing a tire drive gear adaptor to operate the speedometer from one of the bicycle wheel tires does provide accurate speed indication, but requires substantial gear reduction due to the high tire velocity. The large number of gears and bearings necessary for substantial gear reduction also results in an expensive drive.
Additionally, tire drive gear adaptor assemblies are mounted on the bicycle fork for facile engagement with the front tire. In this position, there is a relatively short distance between the gear adaptor assembly and the speedometer, which is mounted on the handlebars at the front of the bicycle. Due to the short distance and the projection of the speedometer boss in a forward direction, the flexible shaft, which transmits movement between the gear adaptor assembly and speedometer, is often difficult to connect without being bent at a sharp angle with a minimum radius.